Trimming material configuration

Abstract

Herein is provided a resonator (100), the resonator (100) comprising at least a first region (201), and a second region (202), wherein the first region (201) comprises at least a top electrode layer (L1), and wherein the second region (202) comprises at least a trimming material layer (212) Herein is further provided an apparatus, such as a resonator array, comprising at least one resonator (100). Herein is further provided a method for matching trimming rates of the first region (201) and the second region (202) of the resonator (100).

Description

[0001] TRIMMING MATERIAL CONFIGURATION

[0002] TECHNICAL FIELD

[0003] The present disclosure generally relates to the field of semiconductors and semiconductor devices. The disclosure relates particularly, though not exclusively, to trimming material configurations of resonators.

[0004] BACKGROUND

[0005] This section illustrates useful background information without admission of any technique described herein representative of the state of the art.

[0006] There is an ongoing need to provide resonators with good quality factor Q. The quality factor Q may be adversely impacted by the thermoelastic dissipation (TED) within the resonator. More specifically, the material choices of the resonator have an effect of the TED of the resonator.

[0007] Resonators, such as quartz crystals or microelectromechanical systems, MEMS, resonators typically require trimming, particularly frequency trimming, in order to adjust and correct their resonance frequency. The characteristics of the device may be negatively impacted by the trimming process.

[0008] SUMMARY

[0009] The appended claims define the scope of protection. Any examples and technical descriptions of apparatuses, products and / or methods in the description and / or drawings not covered by the claims are presented not as embodiments of the invention but as background art or examples useful for understanding the invention.

[0010] It is an object of certain embodiments of the present disclosure to solve problem(s) existing in existing technology, or at least to provide an alternative solution to existing technology.Accordingly, certain disclosed embodiments provide a resonator having good quality factor Q that are trimmable without performance degradation.

[0011] According to a first example aspect of the present disclosure there is provided a resonator, the resonator comprising at least a first region, and a second region, wherein the first region comprises at least a top electrode layer, and wherein the second region comprises at least a trimming material layer.

[0012] In certain embodiments, the top electrode layer is the topmost layer (of the material stack) of the first region. In certain embodiments, the top electrode layer comprises patterns (line(s), perforation(s) or both). In certain embodiments, the top electrode layer comprises patterns, such as perforations, lines or both. In certain embodiments, the patterns of the top electrode layer provide a pathway to charge carrier (to travel within the top electrode). In certain embodiments, the pathway is a meandering pathway (having plurality of turns). In certain embodiments, the top electrode comprises patterns (made, formed, arranged, etched) therein (or within). In certain embodiments, the top electrode comprises patterns within the top electrode (layer). In certain embodiments, the top electrode (layer) comprises (contains, has) patterns where the top electrode layer (material) is absent. In certain embodiments, the pattern is an area (a shape) where the top electrode (material, layer) is (selectively) removed. In certain embodiments, said patterns are formed by patterning the top electrode layer.

[0013] In certain embodiments, the patterns are configured to reach (extend) to (into) the layer(s) beneath the top electrode (layer). In certain embodiments, the patterns of the top electrode layer continue through the top electrode layer. In certain embodiments, the patterns of the top electrode layer continue through the top electrode layer to the piezoelectric layer. In certain embodiments, patterns of the top electrode layer are configured to expose the layer(s) beneath the top electrode. In certain embodiments, the patterns are configured to expose the piezoelectric layer beneath the top electrode.

[0014] In certain embodiments, the top electrode (layer) is a uniform layer (of material). In certain embodiments, the top electrode (layer) covers (essentially) the entire (top, topmost) surface of the first region of the resonator. In certain embodiments, the top electrode layer is a uniform layer (of material) except where the top electrode layer comprises (contains, has) patterns. In certain embodiments, the top electrode (layer) covers (essentially) the entire (top, topmost) surface of the first region of the resonator except where the top electrode (layer) comprises (contains, has) patterns.In certain embodiments, the patterns are openings (opening patterns) within the top electrode layer. In certain embodiments, the top electrode layer comprises patterns in the form of line(s) (grooves), perforation(s) (holes) or both. In certain embodiments, the perforations are round (disk), hexagonal, rectangular, or triangular in shape, or a combination of the preceding. In certain embodiments, the patterns (openings, opening patterns) have an arbitrary shape (are arbitrarily shaped).

[0015] In certain embodiments, the lines are individual lines, or ‘joined’ lines, thereby forming angles and / or meanders. In certain embodiments, the lines are straight lines, angled lines, or curved lines, or the combination of the preceding type of lines. In certain embodiments, the patterns reach through the top electrode layer in z-direction. In certain embodiments, patterns of the top electrode layer expose the layer beneath the top electrode layer. In certain embodiments, the top electrode layer is a holey (perforated) top electrode.

[0016] In certain embodiments, the patterns of the top electrode layer are arranged (provided, placed, deposited, patterned) throughout (everywhere, uniformly) the top electrode layer. In certain embodiments, the patterns of the top electrode layer create a mesh (net) of patterns, such as a mesh of perforations. In certain embodiments, the patterns of the top electrode layer are arranged (on)to the top electrode layer of the resonating element. In certain embodiments, the patterns of the top electrode layer are arranged to the top electrode layer of the beam resonating element.

[0017] In certain embodiments, the trimming material layer is the topmost layer (of the material stack) of the second region. In certain embodiments, the trimming material layer is in a form of patterns. In certain embodiments, the trimming material layer is in a form of patterns, such as localized feature(s) line(s) or both. In certain embodiments, the localized feature(s) (island(s), dot(s), perforation(s)), are round (disk-shaped), hexagonal, rectangular, or triangular in shape, or a combination of the preceding. In certain embodiments, the trimming material layer (being in the form of) patterns has / have an arbitrary shape (is / are arbitrarily shaped). In certain embodiments, the trimming material is present (only) in the patterns. In certain embodiments, the trimming material is present in the patches (raised patterns). In certain embodiments, the trimming material is removed from everywhere else except in the patterns.

[0018] In certain embodiments, the trimming material (layer) is arranged (provided, placed, deposited, patterned) in areas of the resonator having high displacement of the resonance mode. In certain embodiments, the trimming material patterns are provided in highdisplacement areas of the resonance mode (of the resonator). In certain embodiments, the trimming material (layer) is absent from the high strain areas of the resonance mode (of the resonator).

[0019] In certain embodiments, the resonator comprises at least one first region. In certain embodiments, the resonator comprises at least one second region. In certain embodiments, the resonator comprises more than one (a plurality of) first regions (or sub-regions of the first region). In certain embodiments, the resonator comprises more than one (a plurality of) second regions (of sub-regions of the second region).

[0020] In certain embodiments, the first region and the second region each comprise at least one dimension that is different from the corresponding dimension of the other region. In certain embodiments, one dimension of the first region is different from the corresponding dimension of the second region. In certain embodiments, length (dimension) of the first region is different from the length (dimension) of the second region. In certain embodiments, width (dimension) of the first region is different from the width (dimension) of the second region.

[0021] In certain embodiments, the resonator comprises at least a first region, and a second region, and wherein material stacks of the first region and the second region are different from one another. In certain embodiments, material stacks of the first region and the second region are different from one another with respect to the number of material layers they comprise. In certain embodiments, material stacks of the first region and the second region are different from one another with respect to the type of material layers they comprise. In certain embodiments, material stacks of the first region and the second region are different from one another with respect of the material layers they comprise. In certain embodiments, the material stack of the first region comprises all the materials of the resonator’s material stack. In certain embodiments, the material stack of the first region comprises a full material stack. In certain embodiments, the material stack of the first region is the (only) region of the resonator comprising all the materials of the resonator’s material stack. In certain embodiments, the material stack of the first region is the only region of the resonator comprising all the materials of the resonator’s material stack, such that the material stack of the second (third, fourth...) region comprises fewer material layers than the material stack of the first region.

[0022] In certain embodiments, material stacks of the first region and the second region are different from one another (differ from one another, different in comparison to each other,different than each other). In certain embodiments, the resonator is divided into (at least) the first and the second region. In certain embodiments, the material stack of the first region comprises a top electrode layer, a piezoelectric layer, and a silicon layer, wherein the piezoelectric layer is on the silicon layer, and the top electrode layer is on the piezoelectric layer. In certain embodiments, the material stack of the first region comprises the top electrode layer is on the piezoelectric layer, and the silicon layer is on the opposite side of the piezoelectric layer than the top electrode layer. In certain embodiments, the material stack of the first region comprises the silicon layer, the piezoelectric layer on top of the silicon layer, and a top electrode layer on top of the piezoelectric layer.

[0023] In certain embodiments, the top electrode layer is the topmost layer of the resonator (the material stack of the resonator, the material stack of the first region). In certain embodiments, the top electrode layer is implemented by a layer of metal. In certain embodiments, the top electrode layer is a metallic top electrode. In certain embodiments, the top electrode layer comprises (is of, is made of, is fabricated from, contains) metal, preferably gold (Au). In certain embodiments, the top electrode layer comprises metal, such as gold (Au), aluminium (Al), or molybdenum (Mo). In certain embodiments, the top electrode layer is of gold, preferably doped gold. In certain embodiments, the top electrode layer is of gold alloy. In certain embodiments, the top electrode layer is implemented by a layer of doped silicon. In certain embodiments, the top electrode layer is implemented by a layer of doped polysilicon.

[0024] In certain embodiments, the top electrode layer has a thickness in a range of 0.05 pm to 0.6 pm. In certain embodiments, the top electrode layer has a thickness in a range of 0.1 pm to 0.4 pm, such as 0.25 pm.

[0025] In certain embodiments, the trimming material layer is the topmost layer of the resonator (the material stack of the resonator, the material stack of the second region). In certain embodiments, the trimming material layer is implemented by a layer of metal. In certain embodiments, the trimming material layer comprises (is of, is made of, is fabricated from, contains) metal, preferably gold (Au). In certain embodiments, the trimming material layer comprises metal, such as gold (Au), tantalum (Ta), platinum (Pt), titanium (Ti), tungstentitanium (TiW), aluminium (Al), copper (Cu), molybdenum (Mo), or any combination of the preceding. In certain embodiments, the trimming material layer is of gold, preferably doped gold. In certain embodiments, the trimming material layer is of gold alloy.In certain embodiments, the trimming material layer has a thickness in a range of 0.05 pm to 0.6 pm. In certain embodiments, the trimming material layer has a thickness in a range of 0.1 pm to 0.4 pm, such as 0.25 pm.

[0026] In certain embodiments, a bottom electrode of the resonator is implemented by the silicon layer. In certain embodiments, the bottom electrode comprises (is of, is implemented by) silicon. In certain embodiments, the bottom electrode is implemented by a doped silicon layer. In certain embodiments, the bottom electrode implemented by the silicon layer comprises doped silicon, such as ultra-heavily doped, UHD, silicon. In certain embodiments, the bottom electrode comprises silicon, preferably doped silicon, such as ultra-heavily doped, UHD, silicon. In certain embodiments, the silicon layer is a doped silicon layer. In certain preferred embodiments, the silicon is of single-crystalline silicon.

[0027] In certain embodiments, the bottom electrode layer is a metallic bottom electrode. In certain embodiments, the bottom electrode layer is implemented by a layer of metal. In certain embodiments, the bottom electrode layer comprises (is of, is made of, is fabricated from, contains) metal, preferably molybdenum (Mo).

[0028] In certain embodiments, the silicon layer comprises local doping. In certain embodiments, the silicon layer (substrate) further comprises undoped silicon. In certain embodiments, the doped silicon is of N-type or P-type doping. In certain embodiments, the doped silicon comprises n-type doping. In certain embodiments, the doped silicon comprises n++ doping. In certain embodiments, the doping comprises phosphorous doping. In certain embodiments, the doped silicon comprises arsenic doping. In certain alternative embodiments, the doped silicon comprises p-type doping. In certain embodiments, the doped silicon comprises p++ doping. In certain embodiments, the doping comprises boron doping. In certain embodiments, the doped silicon comprises gallium doping. In certain embodiments, the doping comprises an average impurity concentration of at least 1*1019cm-3or more. In certain embodiments, the doping comprises an average impurity concentration of at least 2*1019cm-3or more, such as 102° cm-3or more.

[0029] In certain embodiments, the resonator is a piezoelectric resonator. In certain embodiments, the piezoelectric layer is a piezoelectric transducer layer. In certain embodiments, the piezoelectric layer is of piezoelectric material. In certain embodiments, the piezoelectric layer is of aluminium nitride, AIN. In certain embodiments, the piezoelectric layer is of scandium-doped aluminium nitride, Sc-doped AIN. In certain embodiments, thepiezoelectric layer has a thickness in a range of 1 pm to 3 pm. In certain embodiments, the piezoelectric layer has a thickness in a range of 1.3 pm to 1.7 pm, such as 1.5 pm.

[0030] In certain embodiments, the material stack of the second region comprises a silicon layer. In certain embodiments, the second region comprises silicon, such as doped silicon, such as ultra-heavily doped, UHD, silicon. In certain embodiments, the material stack of the second region contains a silicon layer and a trimming material layer. In certain embodiments, the material stack of the second region comprises a silicon layer and the trimming layer on the silicon layer. In certain embodiments, the second region is absent from the piezoelectric layer (comprises no piezoelectric layer). In certain embodiments, the second region is absent from the top electrode layer (comprises no top electrode layer).

[0031] In certain embodiments, the resonator further comprises a third region (or a further / additional region). In certain embodiments, the resonator further comprises a third region (or a further / additional region), wherein material stack of the third region differs from the material stacks of the first region and the second region. In certain embodiments, the material stacks of the first region, the second region and the third region (or a further / additional region) are different from one another (differ from one another, different in comparison to each other, different than each other). In certain embodiments, material stack of the third region comprises a piezoelectric layer, and a silicon layer. In certain embodiments, material stack of the third region comprises a piezoelectric layer, and a silicon layer, wherein the piezoelectric layer is on the silicon layer.

[0032] In certain embodiments, the resonator further comprises a fourth region (or a further / additional region). In certain embodiments, the resonator further comprises a fourth region (ora further / additional region), wherein material stack of the fourth region differs from the material stacks of the first region and the second region. In certain embodiments, the resonator further comprises a fourth region (or a further / additional region), wherein material stack of the fourth region differs from the material stacks of the first region, the second region and the third region. In certain embodiments, the material stacks of the first region, the second region, the third region and the fourth region (or a further / additional region) are different from one another (differ from one another, different in comparison to each other, different than each other). In certain embodiments, material stack of the fourth region comprises at least a trimming material layer. In certain embodiments, material stack of the fourth region comprises a trimming material layer and a silicon layer. In certain embodiments, material stack of the fourth region comprises a trimming material layer and a silicon layer, wherein the trimming material layer is on the silicon layer.In certain embodiments, the material stacks of all the regions of the resonator are different from one another (differ from one another, different in comparison to each other, different than each other). In certain embodiments, the resonator comprises a plurality of regions, each having a different (varying, not same) material stack with each other. In certain embodiments, the resonator comprises at least two regions, each having a different material stack with each other. In certain embodiments, the resonator is divided into a plurality of regions, each having a different material stack with each other.

[0033] In certain embodiments, the resonator is designed to comprise at least two regions, one with ‘full' material stack and another with silicon (substrate) and a trimming material layer (only). In certain embodiments, the resonator comprises the first region and the second region, wherein the first region contains ‘full1material stack, and the second region contains silicon (substrate) and a trimming material layer only. In certain embodiments, the full material stack comprises a silicon layer (substrate), a piezoelectric layer, and a top electrode layer (in that order, starting from the lowest layer). In certain embodiments, the material stack of the second region comprises a silicon layer (substrate), and a trimming material layer (in that order, starting from the lowest layer). In certain embodiments, the silicon layer of the first region and the second region is the same silicon layer (the regions share a silicon layer / substrate).

[0034] In certain embodiments, the first region and the second region are separated by one another by trench(es) and / or isolation regions. In certain embodiments, the isolation region comprises electrically insulating material (layer), such as the piezoelectric material (layer). In certain embodiments, the isolation region comprises a silicon layer and an insulating material layer. In certain embodiments, the isolation region comprises a silicon layer and a piezoelectric material layer. In certain embodiments, the material stack of the isolation region comprises a silicon layer and the insulating material layer on the silicon layer. In certain embodiments, the isolation region prevents (is configured to prevent) a short circuit between the first region and the second region.

[0035] In certain embodiments, the first region is provided for transduction purposes. In certain embodiments, the first region enables transduction for the resonator. In certain embodiments, the ‘full1material stack region is provided for transduction purposes. In certain embodiments, the ‘full' material stack region enables transduction for the resonator.

[0036] In certain embodiments, the second region is provided for high quality factor, Q, purposes. In certain embodiments, the second region enables high quality factor, Q, for the resonator.In certain embodiments, the first region is for providing transduction of the resonator, and the second region is for providing high quality factor, Q, of the resonator.

[0037] In certain embodiments, all the regions combined cover the entire surface (area) of the resonator. In certain embodiments, each of the regions cover only partially (partly, not fully) the surface area of the resonator (as seen (looked, observed) from above (top view, from up to down)). In certain embodiments, the first (second, third, fourth, further) regions covers less than 60% of a surface area of the resonator. In certain embodiments, the first (second, third, fourth, further) regions covers less than 50% of a surface area of the resonator. In certain embodiments, a ratio of the first region to the second region (full material stack region to silicon-only region) is optimized to balance the (desired) quality factor, Q, and equivalent series resistance, ESR.

[0038] In certain embodiments, the regions covering partially the surface area of the resonator are provided (manufactured, fabricated) via deposition, such as via sputtering. In certain embodiments, the regions covering partially the surface area of the resonator are provided (manufactured, fabricated) via patterning and etching. In certain embodiments, the regions are patterned using lithography.

[0039] In certain embodiments, the resonating element of the resonator comprises at least a first region, and a second region. What is above disclosed in the context of the resonator comprising the first and the second region, applies also herein in the context of the resonating element comprising the first and second regions.

[0040] In certain embodiments, the resonating element is separated from the support structure by a cavity, rendering the resonating element to be encircled by a trench (trenches). In certain embodiments, the resonating element is surrounded by trenches in all sides thereof.

[0041] In certain embodiments, the resonator comprises at least one resonating element. In certain embodiments, the resonator comprises at least one resonating plate element.

[0042] In certain embodiments, the resonating element comprises a plurality of resonating elements, such as resonating beam elements. In certain embodiments, the resonating element comprises a plurality of resonating sub-elements, such as resonating beam elements.

[0043] In certain embodiments, the resonator comprises a resonating element, or a plurality of resonating elements. In certain embodiments, the resonator comprises a resonatingelement, or a plurality of resonating elements, wherein the plurality of resonating elements are adjacent to each other in a plane, connected to one another by a coupler. In certain embodiments, the resonating element comprises a plurality of resonating beam elements adjacent to each other in a plane, connected to one another by connection elements and separated from one another by trenches.

[0044] In certain embodiments, the resonating element comprises a plurality of resonating beam elements (resonating beams). In certain embodiments, each beam element is a subelement of the resonator. In certain embodiments, the resonating element comprises a plurality of resonating beam elements side by side in a plane, connected to one another by connection elements and separated from one another by trenches.

[0045] In certain embodiments, the resonating element comprises a plurality of resonating beam elements. In certain embodiments, the resonating beam elements are separated from one another by trenches. In certain embodiments, the resonator comprises a plurality of beam elements having a length and a width. In certain embodiments, the plurality of beam elements are positioned adjacent to each other. In certain embodiments, adjacent beam elements are mechanically connected to each other by connection elements. In certain embodiments, each adjacent beam element is mechanically connected to another beam element by connection elements. In certain embodiments, each adjacent beam element is mechanically connected to another beam element by (at least) two connection elements.

[0046] In certain embodiments, the resonator is a stacked beam resonator. In certain embodiments, the stacked beam resonator comprises a plurality of beam elements positioned side-by-side in a plane. In certain embodiments, the resonating element comprises a plurality of resonating beam elements adjacent to each other in a plane, connected to one another by connection elements and separated from one another by trenches. In certain embodiments, the resonating beam elements are longitudinally aligned within 25 degrees of a <100> crystal direction of silicon.

[0047] In certain embodiments, the plurality of beam elements are positions adjacent to each other in a width direction thereof. In certain embodiments, the plurality of beam elements are positioned adjacent to each other in a width direction of the resonator. In certain embodiments, the beam elements are separated by trenches. In certain embodiments, the beam elements are connected to each other by connection elements.In certain embodiments, the resonator comprises a plurality of beam elements, such as seven, nine, or eleven beam elements. In certain embodiments, said adjacent beam elements are mechanically connected to each other by connection elements. In certain embodiments, the beam elements of the resonator are arranged in a rectangular array configuration.

[0048] In certain embodiments, the resonator (the resonating element) is in the shape of a rectangle. In certain embodiments, the resonator (the resonating element) is in the shape of an elongated rectangle (beam-shaped). In certain embodiments, the resonator (the resonating element) has an aspect ratio (ratio of length to width, when observed from above) different from 1.

[0049] In certain embodiments, the resonator has a length-to-width aspect ratio of less than 1. In certain embodiments, the resonator is attached (supported, anchored, suspended) to a support structure. In certain embodiments, the resonator is attached to a support structure from the outermost beam elements of the resonator. In certain embodiments, the resonator comprises at least one anchor (anchoring point) configured to connect the resonator to, and suspend the resonator from surrounding layers. In certain embodiments the at least one anchor (anchoring point) comprises portions of the piezoelectric layer, the top electrode layer and the bottom electrode.

[0050] In certain embodiments, each beam element is in the shape of a (rectangular) beam. In certain embodiments, each beam element has an aspect ratio (ratio of length to width, when observed from above) different from 1. In certain embodiments, each beam element has a length-to-width aspect ratio of more than 1.

[0051] In certain embodiments, the resonator is on a substrate. In certain embodiments, the resonator is fabricated on a substrate. In certain embodiments, the substrate is a wafer. In certain embodiments, the substrate is a silicon-on-insulator, SOI, wafer. In certain embodiments, the substrate comprises a silicon layer. In certain embodiments, the bottom electrode (layer) is referred to as a substrate or as a silicon layer.

[0052] In certain embodiments, the resonating beam element(s) are longitudinally aligned within 25 degrees of a <100> crystal direction of silicon (of the bottom electrode). Within at least some embodiments the resonating beam element(s) are longitudinally aligned with a <100 crystal direction of the silicon (of the bottom electrode) such that a longitudinal axis of eachresonating beam is within 25 degrees of the <100> crystal direction of the silicon (of the bottom electrode).

[0053] In certain embodiments, the resonating beam element(s) are longitudinally aligned within 45 degrees, or 50 degrees of a <100> crystal direction of silicon (of the bottom electrode). Within at least some embodiments the resonating beam element(s) are longitudinally aligned with a <100> crystal direction of the silicon (of the bottom electrode) such that a longitudinal axis of each resonating beam is within 45 degrees, or 50 degrees of the <100> crystal direction of the silicon (of the bottom electrode).

[0054] In certain embodiments, the resonating beam element(s) are longitudinally aligned within 25 degrees of a

[0100] crystal direction of silicon (of the bottom electrode). Within at least some embodiments the resonating beam element(s) are longitudinally aligned with a

[0100] crystal direction of the silicon (of the bottom electrode) such that a longitudinal axis of each resonating beam is within 25 degrees of the

[0100] crystal direction of the silicon (of the bottom electrode).

[0055] In certain embodiments, the resonating beam element(s) are longitudinally aligned within 25 degrees of a

[0110] crystal direction of silicon (of the bottom electrode). Within at least some embodiments the resonating beam element(s) are longitudinally aligned with a

[0110] crystal direction of the silicon (of the bottom electrode) such that a longitudinal axis of each resonating beam is within 25 degrees of the

[0110] crystal direction of the silicon (of the bottom electrode).

[0056] In certain embodiments, the resonating beam element(s) are longitudinally aligned within 25 degrees of a

[0111] crystal direction of silicon (of the bottom electrode). Within at least some embodiments the resonating beam element(s) are longitudinally aligned with a

[0111] crystal direction of the silicon (of the bottom electrode) such that a longitudinal axis of each resonating beam is within 25 degrees of the

[0111] crystal direction of the silicon (of the bottom electrode).

[0057] In certain embodiments, the resonating (beam) element is a slanted element. In certain embodiments, the slanted element comprises a slanted resonating beam. In certain embodiments, the slanted resonating (beam) element is configured to resonate in its length direction, and wherein a longitudinal axis of the slanted resonating (beam) element is slanted from a <100> direction of silicon. In certain embodiments, said slanting is to reduce the effect of drive level dependency. In certain embodiments, the longitudinal axis is slanted16 to 22 degrees, more preferably 18 to 20 degrees, most preferably 19 degrees from said <100> direction. In certain embodiments, the slanted resonating (beam) element is in the form of a skewed rectangle. In certain embodiments, the slanted resonating (beam) element is in the form of a resonating (beam) element skewed in one (and only one) direction.

[0058] In certain embodiments, the resonating element is a slanted resonator element, wherein a longitudinal axis of the slanted resonating element is tilted from a <100> direction of silicon. In certain embodiments, the slanted resonator element comprises a slanted resonating beam comprising single-crystalline silicon. In accordance with certain embodiments, a slanted resonating element according to published patent application WO2024 / 218431 A1 may be provided herein.

[0059] In certain embodiments, the resonator comprises a plurality of resonating elements adjacent to each other in a plane, connected to one another by a coupler. In certain embodiments, the resonator is a multi-ladder resonator, comprising a plurality of stacked beam resonating elements (forming a ladder-like configuration). In certain embodiments, each resonator comprises a plurality of resonating elements having a plurality of beam elements having a length and a width, wherein the plurality of beam elements are positioned adjacent to each other and adjacent beam elements are mechanically connected to each other by connection elements. In certain embodiments, the plurality of beam elements are separated from each other by trenches. In certain embodiments, the coupler is a slanted coupler. In certain embodiments, the coupler is a slanted coupler, wherein a longitudinal axis of the slanted coupler is tilted from a <100 direction of silicon.

[0060] In certain embodiments, the resonator comprises a plurality of extensional-mode resonating elements. In certain embodiments, the resonator comprises a plurality of length extensionalmode resonating elements. In certain embodiments, the resonator comprises a plurality of flexural-mode resonating elements. In certain embodiments, the resonator comprises a mechanical coupler which connects the resonating elements to one another.

[0061] In certain embodiments, the resonator comprises at least a first region, and a second region, wherein the first region comprises at least one resonating element, and the second region comprises at least another resonating element (area of the resonating element). In certain embodiments, the material stacks of the one resonating element and the another resonating element are different from one another.In certain embodiments, the resonator is configured to resonate (operate, oscillate, vibrate) in an in-plane resonance mode. In certain embodiments, the resonating element 8the resonator) is configured to resonate in a length-extensional, LE, resonance mode. In certain embodiments, the resonator is configured to resonate in an in-plane length-extensional, LE, resonance mode. In certain embodiments, the length extensional resonance mode is configured to resonate parallel to the length direction of the resonator. In certain embodiments, the length extensional resonance mode is configured to resonate perpendicular to the width direction of the resonator.

[0062] In certain embodiments, the resonating element is configured to resonate in a squareextensional, SE, resonance mode. In certain embodiments, the resonating element is configured to resonate in a width-extensional, WE, resonance mode.

[0063] In certain embodiments, the resonator is configured to resonate in a collective resonance mode. In certain embodiments, each resonating element of the resonator is configured to resonate in the (same) collective resonance mode. In certain embodiments, the resonator is configured to resonate in a desired (main) resonance mode. In certain embodiments, each beam element of the resonator is configured to resonate in the (same) desired resonance mode.

[0064] In certain embodiments, the second region of the resonator is configured to resonate in a resonance mode different than the first region. In certain embodiments, the first region and the second region of the resonator are configured to resonate in different resonance modes with one another. In certain embodiments, the first region of the resonator is configured to resonate in a length-extensional, LE, resonance mode. In certain embodiments, the second region of the resonator is configured to resonate in a resonance mode different than the length-extensional, LE, resonance mode.

[0065] In certain embodiments, the resonator is a microelectromechanical systems, MEMS, resonator. In certain embodiments, the resonator is (part of) a semiconductor device. In certain embodiments, the resonator is configured to operate in a megahertz frequency area. In certain embodiments, the resonator is configured to operate at 32 MHz frequency. In certain embodiments, the resonator is configured to operate in an overtone resonance frequency of 32 MHz. In certain embodiments, the resonator is configured to operate in a resonance frequency of 76.8 MHz.According to a second example aspect of the present disclosure there is provided an apparatus, such as a resonator array (an apparatus), comprising at least one resonator according to the first aspect or any of its embodiments. In certain embodiments, the apparatus comprises (at least) two (more than one) resonators of the first aspect or any of its embodiments coupled to each other. In certain embodiments, the apparatus is a semiconductor apparatus, or a semiconductor device.

[0066] According to third example aspect of the present disclosure there is provided a method for matching the trimming rates of the first region and the second region of the resonator according to the first aspect or any of its embodiments, the method comprising the steps of:

[0067] - providing the resonator of the first aspect or any of its embodiments;

[0068] - removing a part of (part(s)) of the top electrode layer of the first region;

[0069] - providing trimming material (layer) onto the second region.

[0070] In certain embodiments, the method comprises adjusting the trimming rates of the first region and the second region to match one another (each other). In certain embodiments, said matching refers to rendering the trimming rates of said regions equal (or at least compatible) with one another.

[0071] As used herein, trimming rate is used to refer to the rate at which material is trimmed from the resonator. In other words, the trimming rate can be called also as ‘trimmability’ or ‘trimming ability’. Typically, trimming is performed by removing parts of the topmost material layer of the device, for instance by ion beam trimming. In certain embodiments, the material coverage of the regions of the resonator are adjusted to achieve the desired frequency and performance characteristics. In certain embodiments, selective addition or removal of material can be used for trimming. In certain embodiments, the top electrode material is removed from the first region, and added to the second region to match the trimming rates of these regions.

[0072] In certain embodiments, the removing of part(s) the top electrode layer of the first region is provided by a selective removal of material. In certain embodiments, the removing the top electrode layer is provided by forming patterns (patterning) to the top electrode layer. In certain embodiments, said forming patterns comprises lithographic patterning followed by etching the top electrode layer. In certain embodiments, the top electrode layer is removed from the first region to reduce (decrease) the trimming rate of the first region.

[0073] In certain embodiments, the providing trimming material onto the second region is provided by selective addition of material. In certain embodiments, said providing trimming materiallayer onto the second region comprises deposition and / or patterning (forming patterns to) the trimming layer material. In certain embodiments, said patterning comprises lithographic patterning followed by etching. In certain embodiments, said providing the trimming material layer onto the second region is to achieve the desired trimming rate of the second region.

[0074] In accordance with certain embodiments, embodiments of the second aspect or third are provided, the embodiments comprising subject matter of any single embodiment presented in connection with the first aspect, the second aspect, or the embodiments comprising subject matter of any of the embodiments presented in connection with the first or the second aspect combined with subject matter presented in any other embodiment or embodiments.

[0075] Different non-binding example aspects and embodiments have been illustrated in the foregoing. The embodiments in the foregoing are used merely to explain selected aspects or steps that may be utilized in different implementations. Some embodiments may be presented only with reference to certain example aspects. It should be appreciated that corresponding embodiments may apply to other example aspects as well. In particular, the embodiments described in the context of the first aspect are applicable to each further aspect. Any appropriate combinations of the embodiments may be formed.

[0076] BRIEF DESCRIPTION OF THE FIGURES

[0077] Some example embodiments will be described with reference to the accompanying figures, in which:

[0078] Fig. 1a schematically shows a top view of an example resonating element structure according to an example embodiment;

[0079] Fig. 1b schematically shows a cross-sectional view of a full material stack of an example resonator according to an example embodiment;

[0080] Fig. 2a schematically shows a top view of a resonating element having two regions according to an example embodiment;

[0081] Fig. 2b schematically shows a top view of a resonating element having two regions with patterns according to an example embodiment;

[0082] Fig. 2c schematically shows a top view of a resonating element having two regions with patterns according to another example embodiment;Fig. 2d schematically shows a cross-sectional view of a resonating element having two regions according to an example embodiment;

[0083] Fig. 3 schematically shows a top view of a multi-ladder resonator according to an example embodiment;

[0084] Fig. 4 schematically shows a top view of an overtone resonator according to another example embodiment;

[0085] Fig. 5 schematically shows a top view of a ‘mix and match’ resonator according to an example embodiment; and

[0086] Fig. 6a schematically shows a top view of a slanted resonator according to an example embodiment; and

[0087] Fig. 6b schematically shows a top view of a multi-ladder resonator with slanted couplers according to an example embodiment.

[0088] DETAILED DESCRIPTION

[0089] In the following description, like reference signs denote like elements or steps.

[0090] As used herein, the term “(semiconductor) apparatus” or “device” refers to any kind of apparatus or device that may appear in a semiconductor industry, such as a chip, circuitry, microchip, microprocessor, silicon chip, computer chip, resonator, sensor, accelerometer, gyroscope, actuator and process-control unit, vacuum tube or alike. In certain embodiments, the semiconductor device has been packaged. The semiconductor apparatus may be a MEMS apparatus.

[0091] As used herein, the term “material stack” refers to the resonator materials that form the cross-sectional layer structure of the resonator. Thus, the term stack refers to a cross-sectional stack, meaning that the materials can be seen on top of each other once observing the cross-section of the resonator. When observed from the top, only the topmost layer of the particular region can be seen. In accordance with certain embodiments, some of the materials of the material stack originate from the substrate itself (such as the silicon layer), and some of the materials are provided / deposited onto the substrate.

[0092] As used herein, the notation “the layer X on the layer Y” refers to the layer X being above the layer Y within the material stack in question. Synonyms for the notation are, by way of example, ‘the layer X on top of the layer Y’, ‘the layer X onto the layer Y’, and ‘the layer Xabove the layer Y’. As used herein, the notation ‘the layer X below the layer Y’ refers to the layer X being underneath the layer Y within the material stack in question. Synonyms for the notation are, by way of example, ‘the layer X under the layer Y’, and ‘the layer X underneath the layer Y’.

[0093] As used herein, the terms “first / second / third / fourth region” refer to an area or areas of the resonator. In accordance with certain embodiments, the “region” may be one area, such as one rectangular shaped area within the resonator. Alternatively, the “region” may be divided into several areas (sub-regions) within the resonator, separated from each other by other region(s) or other resonator features, such as by a coupler or a trench. Regardless of any such division - herein the term “region” encompasses all the divided areas (sub-regions) of the resonator under the one common term “region”. The region(s) are not limited to a particular shape, size and location within the resonator in accordance with certain embodiments. Synonyms for “region” include, but are not limited to a part, section, and area. The regions of the resonator may be observed in top view, wherein the regions can be identified by the different topmost layers in accordance with certain embodiments. The regions of the resonator may also be observed in a cross-sectional side view, wherein the regions can be identified based on the different material stacks thereof and having varying thicknesses in comparison to one another in accordance with certain embodiments.

[0094] Fig. 1a schematically shows a top view (from above, from up to down) of an example resonator demonstrating an example structure thereof according to an example embodiment. In certain embodiments, the resonator 100 comprises a resonating element 101. In certain alternative embodiments, the resonator 100 comprises a plurality of resonating elements 101.

[0095] The resonator 100 according to embodiment shown in Fig. 1a comprises a resonating element 101. The resonating element 101 comprises a plurality of resonating beam elements having a length L and a width W. In certain embodiments, the resonating beam elements are beam elements (beam-shaped). In the embodiment shown in Fig. 1a, the resonating element 101 comprises seven resonating beam elements (the number of beam elements may vary depending on the embodiment). In certain embodiments, the resonating beam elements are longer L than they are wide W. In certain embodiments, the coordinate system is selected so that the x-axis resides in the width direction W of the resonating beam element and the y-axis in the longitudinal direction L of the resonating beam elements.According to the example embodiment shown in Fig. 1a, the plurality of resonating beam elements are positioned adjacent to each other. In certain embodiments, the plurality of resonating beam elements form a ladder-like configuration (stacked beam resonator). In certain embodiments, the plurality of resonating beam elements are positioned adjacent to each other in a width direction thereof. The adjacent resonating beam elements are mechanically connected to each other.

[0096] In certain embodiments, the resonating element is formed of the plurality of resonating beam elements and a plurality of connection elements 102. In certain embodiments, said adjacent resonating beam elements are mechanically connected to each other by connection elements 102 (such as two connection elements 102). In certain embodiments, the adjacent resonating beam elements are separated by trenches 104. In certain embodiments, the trenches 104 have a length TL (trench length). In certain embodiments, the length L of the beam element comprises at least the length of the trench TL and the length of at least one connection element 102.

[0097] In certain preferred embodiments, the resonator 100 is a stacked beam resonator comprising a plurality of resonating beam elements positioned side-by-side in a plane, separated by trenches 104 and connected by connection elements 102. In at least some stacked beam resonators, the resonating beam elements are positioned in the same plane. In certain stacked beam resonators, no two resonating beam elements are positioned atop each other.

[0098] In certain embodiments, the resonating beam elements of the resonating element 101 are arranged in a rectangular array configuration. In certain embodiments, the resonating element 101 has a length L (which is equal to the length of the beam element). In certain embodiments, the resonating element 101 has a width RW (resonating element width).

[0099] In certain embodiments, the resonating element 101 is attached to a support structure (support structure not shown in Fig. 1a). In certain embodiments, the resonating element 101 is suspended to the support structure via an anchoring point 103a / 103b. In certain embodiments, the resonating element 101 is suspended to the support structure via more than one anchoring point 103a / 103b, such as two anchoring points 103a / 103b. In certain embodiments, the resonating element 101 is attached to the support structure 110 from the outermost resonating beam elements by anchoring point(s) 103a / 103b. In certain embodiments, the anchoring points 103a / 103b are connected to respective electrical terminal. In certain embodiments, the electrical terminal(s) are arranged at the anchoringpoint(s) 103a / 103b. In certain embodiments, the resonating element is separated from the support structure 110 by (an external) trench 104’.

[0100] In certain embodiments, the resonating element 101 is of an elongated shape (having the length L smaller than their width RW). In certain embodiments, the resonating element 101 is in the shape of a rectangle (the resonator 100 has a shape of a rectangle). In certain embodiments, the resonating element 101 has an aspect ratio (ratio of length L to width RW, when observed from above) different from 1. In certain embodiments, the resonating element 101 has a length-to-width, L-to-RW, aspect ratio of less than 1.

[0101] In certain embodiments, the resonating beam elements are of an elongated shape (having their length L larger than their width W). In certain embodiments, each resonating beam element is in the shape of a rectangular beam (beam-shaped). In certain embodiments, each resonating beam element has an aspect ratio (ratio of length L to width W, when observed from above) different from 1. In certain embodiments, each resonating beam element has a length-to-width, L-to-W, aspect ratio of more than 1. In certain example embodiments, each resonating beam element has a length-to-width, L-to-W, aspect ratio of more than 2, such as 5, 8, or 10.

[0102] In certain embodiments, the resonator 100 is a megahertz frequency microelectromechanical system, MEMS, resonator. In certain embodiments, the resonator 100 is configured to resonate in an in-plane length-extensional, LE, resonance mode.

[0103] In certain embodiments, the longitudinal axis L of a resonating element 101 (or the resonating beam element) is aligned with <100> crystal direction of the silicon (of the bottom electrode), such as aligned with

[0100] crystal direction of silicon (of the bottom electrode), or deviates less than 25 degrees therefrom, or less than 15 degrees therefrom in certain embodiments. In certain preferable embodiments, the longitudinal axis L of the resonating element 101 is aligned with <100> crystal direction of the silicon (of the bottom electrode), such as aligned with

[0100] crystal direction of the silicon (of the bottom electrode), or deviates less than 5 degrees therefrom, or less than 2 degrees therefrom in certain embodiments.

[0104] Fig. 1b schematically shows a “full” material stack of a resonator according to an example embodiment. Fig. 1b schematically shows an example cross section (sectional view, side view) of the resonating element 101 residing on a substrate. Certain further features of the instant solution are described in detail in the context of Figs. 2a-7e.In certain embodiments, the resonator 100 (and the resonating element 101) is fabricated on a substrate. In the example embodiment of Fig. 1b, a silicon on insulator (SOI) substrate (wafer) 450 is used. The reference numerals 401 and 402 denote bottom electrode and top electrode (top electrode layer) contacts, respectively.

[0105] In certain embodiments, the resonator 100 (and the resonating element 101) comprises a material stack, the material stack comprising at least the silicon layer L4, the piezoelectric layer L2 on top of the silicon layer, and a top electrode layer L1 on top of the piezoelectric layer. In certain embodiments, the top electrode layer L1 is the top electrode of the resonator 100. In certain embodiments, the piezoelectric layer comprises doping, such as scandium doping.

[0106] In the example embodiment shown in Fig. 1b, the top electrode layer is implemented in layer L1. In this example embodiment, layer L2 is a piezoelectric layer for piezoelectric actuation of the resonating element residing in the area of denoted by 101. An opening in L2 is denoted by 420. In this example embodiments, layer L3 denotes a layer for the bottom electrode. In certain embodiments, the bottom electrode layer L3 is a metallic bottom electrode. In certain embodiments, the bottom electrode layer L3 is implemented by a layer of metal, preferably molybdenum (Mo). In this example embodiment, layer L4 is a silicon layer for the resonator (for example resonating beam elements and their connecting elements according to certain embodiments). In this example embodiments, layer L5 is a buried oxide layer (SiO2) of the SOI wafer, and layer L6 is a silicon handle layer. In certain embodiments layer L6 comprises a cavity C1. In certain embodiments, the layer L5 follows the cavity C1 shape as shown in Fig. 1b.

[0107] In certain embodiments, when a doped silicon layer is used as L4, it is possible to leave out the separate L3 bottom electrode. In such embodiments, the conductive doped silicon layer L4 acts as the bottom electrode. In certain embodiments, the silicon layer L4 comprises degenerately doped silicon. In certain embodiments, more than 50 % of the silicon layer L4 mass consists of degenerately doped silicon. In certain embodiments, the silicon layer L4 is doped to an average impurity concentration of at least 2*1019cm-3, such as at least 102° cm-3. In certain embodiments, the doped silicon is of N-type or P-type doping. In certain embodiments, the bottom electrode comprises ultra-heavily doped, UHD, silicon.

[0108] In certain embodiments, the silicon layer L4 comprises single crystalline silicon. In certain embodiments, the silicon layer L4 consists essentially of single crystalline silicon. In certain embodiments, the silicon layer L4 comprises degenerately doped single crystalline silicon.In certain embodiments, more than 50% of the mass of the resonator comprises material portions of single-crystalline silicon.

[0109] In certain embodiments, the resonator 100 (and the resonating element 101) comprises a material stack, the material stack comprising the silicon layer L4 (the bottom electrode), the piezoelectric layer L2 on top of the silicon layer L4, and a top electrode layer L1 on top of the piezoelectric layer L1. In certain embodiments, the resonator 100 is a piezoelectric resonator. In certain embodiments, the resonating element 101 is a piezoelectric resonating element. In certain embodiments, the piezoelectric layer L2 comprises aluminium nitride. In certain embodiments, the top electrode layer L1 is the top electrode of the resonator 100.

[0110] Figs. 2a, 2b and 2c schematically show a top view of a resonating element having regions for frequency and trimming matching according to an example embodiment. The example resonating elements of Figs. 2a, 2b, and 2c corresponds to the example shown in Fig. 1a. Fig. 2d shows a cross section of the line D-D shown in Fig. 2b.

[0111] Herein is provided a resonator 100 (having a resonating element 101), the resonator 100 (the resonating element 101) comprising at least a first region 201, and a second region 202, wherein the first region 201 comprises at least a top electrode layer L1, and wherein the second region 202 comprises at least a trimming material layer 212.

[0112] In certain embodiments, the material stacks of the first region 201 and the second region 202 are different from one another. As shown in Figs. 2a, 2b, 2c and 2d, the resonating element 101 is divided into the first 201 and the second region 202. The first region 201 is shown in Figs. 2a, 2b, 2c and 2d as light grey background, and the second region 202 is shown as darker grey.

[0113] As shown in Figs. 2a, 2b and 2c, the first region 201 comprises two sub-regions (or the resonator 100 comprises two first regions 201), one on each side of the second region 202 in accordance with certain embodiments. In certain embodiments, the first region 201 and / or the second region 202 extend the (entire) length of the resonating element 101 (extending / reaching from one side of the resonating element 101 to another side, extending from a trench 104 to trench 104). In certain embodiments, the first region 201 and / or the second region 202 comprise the area of the resonating beam elements and the connection elements 102.As shown in Figs. 2a, 2b and 2c, in certain embodiments, all the regions 201, 202 combined cover the entire surface (area) of the resonating element 101. In certain embodiments, each of the regions 201, 202 cover partially the surface area of the resonating element 101. In certain embodiments, the first region 201 is provided for transduction purposes, and the second region 202 is provided for high quality factor, Q, purposes. Accordingly, the first region 201 can be called a ‘high transduction’ region 201, and the second region can be called a ‘high quality factor, Q’ region 202.

[0114] In certain embodiments, the first region 201 is arranged on the proximity of the anchoring point(s) 103a / 103b. In certain embodiments, the first region 201 is arranged to contact the anchoring point(s) 103a / 103b. In certain embodiments, the first region 201 enabling the transduction for the resonating element 101 arranged to contact the anchoring point(s) 103a / 103b provides an electrical connection from the electrical terminals through the anchoring point(s) 103a / 103b to the resonating element 101. In certain embodiments, the transducing beam elements of the first region 201 are placed externally (outer regions, outermost areas) for easier electrical connection to pads through the anchoring points (pads are not shown in Figs. 2a, 2b and 2c).

[0115] As shown in Figs. 2a, 2b and 2c, in certain embodiments, the top electrode layer L1 comprises patterns 211. In certain embodiments, the top electrode layer L1 comprises perforations (holes), lines (grooves) or both. In the embodiments of Figs. 2a and 2b, the top electrode layer L1 comprises perforations (holes). In the embodiment of Fig. 2c, the top electrode layer L1 comprises lines (grooves). In certain embodiments, the lines are straight. In certain embodiments, the lines are bendy, curvy or meandering.

[0116] In certain embodiments, the top electrode layer L1 is an otherwise uniform layer of material, except in patterns 211 where the top electrode layer L1 material is removed. In certain embodiments, said patterns 211 are formed by patterning the top electrode layer L1.

[0117] In certain example embodiments, such as shown in Figs. 2a and 2b, the resonating element 101 comprises a perforated (holey) top electrode L1, wherein the perforations 211 reach through one or more material layers of the top electrode L1. In certain embodiments, the perforations 211 have the shape of circles, hexagons, hexagons with triangle extensions, crosses, rectangles, triangles or ellipses. In certain embodiments, all the perforations 211 are identical. In certain alternative embodiments, the first region 201 of the resonating element 101 comprises different kinds of perforations 211 in comparison to the secondregion 202. In at least some embodiments, the patterns, such as perforations 211 are uniformly spaced, creating a mesh, as shown in Figs. 2a and 2b.

[0118] In certain example embodiments, such as shown in Fig. 2c, the resonating element 101 comprises a groovy top electrode L1 (having lines), wherein the lines 211 reach through one or more material layers of the top electrode L1. In certain embodiments, the lines 211 have the cross-sectional shape of a rectangle, ellipse (U-shape), triangular (V-shape) or any other suitable shape that results in a groove formed onto the top electrode layer L1. In certain embodiments, all the lines 211 are identical. In certain alternative embodiments, the first region 201 of the resonating element 101 comprises different kinds of lines 211 in comparison to the second region 202. In at least some embodiments, the patterns, such as lines 211 are uniformly spaced. In certain embodiments, the patterns 211, such as lines, are arranged as to provide a pathway to charge carriers within the top electrode layer L1. In certain embodiments, the pathway is a meandering pathway (like a maze, and / or having a plurality of turns).

[0119] In certain embodiments, the patterns, such as perforations or lines 211 are comprised in columns and / or rows along the first region 201 of the resonating element 101. In certain embodiments, the adjacent columns and / or rows of patterns, such as perforations or lines 211 are off-set from each other. In some embodiments, the patterns, such as perforations or lines 211 are equally spaced throughout the first region 201 of the resonating element 101. In certain embodiments, the patterns 211, such as perforations or lines, are arranged in adjacent to one another along the length and / or the width of the resonating element 101. In certain embodiments, the patterns 211, such as perforations or lines, are arranged adjacent to one another along the y-axis and / or the x-axis of the resonating element 101. In certain embodiments, the patterns 211, such as perforations or lines are randomly (arbitrarily) arranged within the top electrode layer L1.

[0120] Patterns 211, such as perforations or lines according to certain embodiments may be provided in a variety of fashions. For example, certain embodiments employ lithographic patterning. Etching may be employed with at least some embodiments. For example, after lithography, one or more (successive) etching steps are employed to achieve certain embodiments. In certain embodiments, the etching may be wet etching, or dry etching. In certain embodiments, the etching is a deep reactive ion, DRIE, etching.

[0121] As shown in Figs. 2a, 2b and 2c, the second region 202 comprises a trimming material 212. In certain embodiments, the trimming material 212 is arranged in areas of resonatingelement 101 (the resonator 100) having high displacement of the resonance mode. In the example embodiments shown in Figs. 2a, 2b and 2c, the trimming material 212 is arranged in the peripheral areas of the second region 202. In an embodiment of in-plane lengthextensional resonance mode, the area of highest displacement of the resonance mode is in the peripheral areas of a stacked beam resonator 100. In certain embodiments, the trimming material 212 is absent from the high strain areas of the resonance mode, which in this embodiment is in the central area of the second region 202 of the resonating element 101. The peripherals of the resonating element 101 are a point of low strain and stress, whilst the central areas are a point of high strain and stress. Thus, provision of the trimming material 212 in the peripheral areas enables providing low thermoelastic dissipation, TED, losses.

[0122] In the embodiment of Fig. 2a, the trimming material is in a form of a trimming material layer 212. In certain embodiments, the trimming material layer 212 is a uniform material layer, covering at least partially the (surface of) second region 202.

[0123] In certain embodiments, the trimming material layer is in a form of patterns 212, such as localized features, lines or both. In certain embodiments, such as shown in Fig. 2b, the trimming material layer is in a form of localized features (dots, patches). In certain embodiments, such as shown in Fig. 2c, the trimming material layer is in a form of lines (elongated raised features).

[0124] In at least some embodiments, the patterns 212, such as localized features or lines, are uniformly spaced. In certain embodiments, the patterns 212, such as localized features or lines, are comprised in columns and / or rows along the second region 202 of the resonating element 101. In certain embodiments, the adjacent columns and / or rows of patterns 212, such as localized features or lines, are off-set from each other. In some embodiments, the patterns 212, such as localized features or lines, are equally spaced throughout the second region 202 of the resonating element 101.

[0125] In certain embodiments, the patterns 212, such as localized features or lines, are arranged in adjacent to one another along the length and / or the width of the resonating element 101. In certain embodiments, the patterns 212, such as localized features or lines, are arranged in adjacent to one another along the y-axis and / or the x-axis of the resonating element 101. In certain embodiments, the patterns 212, such as localized features or lines are randomly (arbitrarily) arranged within the trimming layer.As shown in Figs. 2b and 2c, in certain embodiments, the trimming material 212 is present only in the area of the patterns. In these embodiments, the trimming material 212 is removed from everywhere else except in the patterns (patches, raised features of trimming material). The shaping of the trimming material 212 enables preventing the trimming material of the second region 202 from affecting or decreasing the quality factor Q or causing any adverse effect on the resonance frequency stability. Further, in accordance with certain embodiments, the shaping of the trimming material 212 enables preventing thermoelastic dissipation, TED losses of the resonator. Yet further, in accordance with certain embodiments, the shaping of the trimming material 212 enables minimal stress / strain modulation caused by the trimming material 212, which enables good frequency stability.

[0126] Since the trimming material is for trimming purposes, no electrical contact / transduction is needed into the trimming material 212 in accordance with certain embodiments. Hence, there is no need to create a mesh of connections, or a pathway to charge carriers.

[0127] Since the top electrode layer of an electrode layer, an electrical contact (voltage, current) is provided into the top electrode layer L1 in accordance with certain embodiments. In certain embodiments, electricity flows within the top electrode layer.

[0128] As used herein, a distinction should be made between a layer comprising patterns, and a material of a layer being in a form of patterns. This is elaborated above in context of Figs, 2a, 2b and 2c, and shown below in context of Fig. 2d. In accordance with certain embodiments, the layer that comprises patterns should be understood as otherwise uniform or ‘intact’ layer of material, except in specific parts (patterns) wherein the material has been removed. In accordance with certain embodiments, the material that is in a form of a pattern (or a shape) should be understood such that the material is only present in specific areas that are in shape pf patterns. All other material of said layer has been removed.

[0129] In a way, the definition “a layer comprising patterns” is the opposite of the definition “material of a layer being in a form of patterns”. This is to say that the opposite part of the material is removed in each case. In the first case, the material of said layer is absent in the area of the patterns, and in the second case, the material of said layer is present only in the area of the patterns. In accordance with certain embodiments, the first region 201 comprises the top electrode layer comprising patterns (the first case) and the second region 202 comprises a trimming layer 212 that is in form of patterns (the second case). This is shown below in context of Fig. 2d. In accordance with certain embodiments, the top electrode layer L1 of the first region 201 provides a pathway for charge carriers (electrical connection), whilst thetrimming material 212 of the second region 202 is not coupled to any electrical connection, and hence no pathway for the charge carriers is provided.

[0130] In certain embodiments, the provision of the trimming material 212 enables trimming of the resonator frequency. In certain embodiments, the provision of the trimming material 212 further enables matching the resonance frequencies of the different regions. In certain embodiments, the trimming material 212 is provided to the second region 202 to enable matching the trimming rate between the first region 201 and the second region 202. In certain embodiments, the amounts of top electrode material L1 and the trimming material 212 are optimized with respect to each other in order to provide same trimming rate between the regions 201, 202.

[0131] As used herein, trimming rate is used to refer to the rate at which material is trimmed from the resonator. In other words, the trimming rate can be called also ‘trimmability’ or ‘trimming ability’. In trimming, the regions of the resonator are adjusted to achieve the desired frequency and performance characteristics. Herein, the top electrode material is removed from the first region, and trimming material is added to the second region to match the trimming rates of these regions. Specifically, it involves removing the material on the transducer, T, region (the first region 201) to reduce its trimming rate, adding material on the high quality factor Q, HQ, region (the second region 202), and matching their trimmabilities with each other.

[0132] In case there is no trimming layer 212 in the second region 202 (the high-quality factor, HQ, region), the trimming process would cause the frequencies of the individual regions (the first region 201 and the second region 202) to get mismatched. This results in the quality factor, Q dropping. The embodiments of the instant solution according to the instant disclosure fixes that problem.

[0133] According to certain embodiments, herein is provided a method for matching the trimming rates of the first region 201 and the second region 202 of the resonator 100, the method comprising the steps of: providing the resonator 100; removing parts of the top electrode layer L1 of the first region 201; providing trimming material 212 onto the second region 202. In certain embodiments, the method comprises adjusting the trimming rates of the first region 201 and the second region 202 to match one another (each other) such that the trimming rates are compatible with one another.In certain embodiments, the partial removal of the top electrode layer L1 is provided by forming patterns, such as perforations to the top electrode layer L1. In certain embodiments, the patterns are formed such that the charge carriers are able to travel within the top electrode layer (the travelling of the charge carriers is not prevented). In accordance with certain embodiments, the removal of top electrode material L1 reduces the trimming rate of the first section 201. Further, in accordance with certain embodiments, the removal of top electrode material L1 increases the quality factor of the resonator.

[0134] In accordance with certain embodiments, selective addition (or selective removal of) material can be used for trimming. In certain embodiments, said providing trimming material 212 onto the second region 202 comprises selective deposition of the trimming material 212, or uniform deposition of trimming material 212 followed by patterning. In certain embodiments, the trimming material 212 is provided in form of shapes (patterns). In certain embodiments, no pathway for charge carrier is provided into the trimming material layer, or within the trimming material layer. In accordance with certain embodiments, the addition of trimming material 212 enables trimming of the resonator.

[0135] As shown in Figs. 2a and 2b, the first region 201 and the second region 202 are separated from each other by isolation regions 215 and trenches 104. In certain embodiments, the isolation region 215 comprises electrically insulating material, such as the piezoelectric material. In certain embodiments, the isolation region 215 comprises a silicon layer L4 and a piezoelectric material layer L2 on top of the silicon layer L4. In certain embodiments, the isolation region 215 prevents a short circuit between the first region 201 and the second region 202.

[0136] The resonance frequency of the resonator depends on electrode or metal coverage. In context of the present disclosure, the frequency of the first region 201 depends on the coverage of the top electrode layer L1. Analogously, the frequency of the second region 202 depends of the coverage of the trimming material 212. Since the coverages of the top electrode L1 and the trimming material 212 are adjusted herein for the trimming rate purposes, the dimensions both sections are re-adjusted in accordance with certain embodiments. As shown in Figs. 2a and 2b, in certain embodiments, the resonating element 101 in area of the first region 201 and the resonating element 101 in area of the second region 202 have different dimensions in comparison to one another. The corresponding dimension D1, D2 may be, by way of examples, length, width, diameter, radius, or any other dimension observable from the resonating element 101. In the examples shown in Figs. 2aand 2b, the corresponding dimension (that is different between the regions) is the length of the resonating element (marked as L in Fig. 1a).

[0137] As shown in Fig. 2a, in certain embodiments, the corresponding dimension D1 of the first region 201 is smaller than the corresponding dimension D2 of the second region 202. As shown in Fig. 2b, in certain embodiments, the corresponding dimension D1 of the first region 201 is larger than the corresponding dimension D2 of the second region 202. In certain embodiments, the difference between the dimension D1 and the dimension D2 is in the range of 0.1 pm to 1 pm, preferably in the range of 0.2 pm to 0.6 pm, such as 0.4 pm.

[0138] In accordance with certain embodiments, the change of dimension(s) within the resonating element 101 enables tuning the resonating element 101 geometry to achieve matching resonance frequencies of the different regions. In certain embodiments, all the regions of the resonator are configured to resonate in the same resonance frequency. In certain embodiments, the thickness of the piezoelectric layer is varied (adjusted, changed, designed) to adjust (optimize, change, design) the resonance frequency of the first region 201. This also provides an aid in matching resonance frequencies of the different regions.

[0139] In certain further embodiments, to achieve the collective resonance and the matching of the resonance frequencies, the combination of the dimension tuning and the patterns, such as perforations (and / or other patterns that achieve the same effect) of the top electrode layer L1 and the trimming material layer 212 are used.

[0140] Fig. 2d schematically shows a cross-sectional view of a resonating element 101 having two regions 201, 202 according to an example embodiment.

[0141] As shown in Fig. 2d, in certain embodiments, material stacks of the first region 201 and the second region 202 differ from each other. In certain embodiments, the material stack of the first region 201 comprises all the materials of the resonator’s 100 material stack, rendering the first region 201 to a full material stack region 201 (an example of a ‘full’ stack resonator 100 is also shown in the Fig. 1b). As shown in Fig. 2d, in certain embodiments, the material stack of the first region 201 comprises a top electrode layer L1 , a piezoelectric layer L2, and a silicon layer L4, wherein the piezoelectric layer L2 is on the silicon layer L4, and the top electrode layer L1 is on the piezoelectric layer L2.

[0142] Optionally, the material stack of the first region 201 comprises a bottom electrode layer L3 (not drawn in Fig. 2b, but visible in Fig. 1b). In certain preferred embodiments, like shown in Fig. 2d, the bottom electrode of the resonator 100 is implemented by the silicon layer L4.In certain embodiments, the bottom electrode implemented by the silicon layer L4 comprises doped silicon, such as ultra-heavily doped, UHD, silicon, having the average impurity concentration of at least 1*1019cm-3or more, such as at least 2*1019cm-3or more, such as 102° cm-3or more.

[0143] As shown in Fig. 2d, in certain embodiments, the top electrode layer L1 is the topmost layer of the material stack of the first region 201. In certain embodiments, the top electrode layer L1 comprises metal, such as gold (Au), aluminum (Al), or molybdenum (Mo). In certain embodiments, the top electrode layer L1 has a thickness in a range of 0.05 pm to 0.6 pm, preferably in a range of 0.1 pm to 0.4 pm, such as 0.25 pm.

[0144] In certain embodiments, the top electrode layer L1 is a patterned (holey, perforated, comprises openings, opening patterns) top electrode L1. In certain embodiments, the patterns 211, such as holes or perforations, are configured to reach (extend) through the top electrode layer 211 in z-direction, as shown in Fig. 2d.

[0145] In certain embodiments, patterns 211 of the top electrode layer L1 expose the layer beneath the top electrode layer L1, in this embodiment the piezoelectric layer L2. In certain alternative embodiments, the patterns 211 reach into (or completely through) the layer beneath the top electrode layer L1 , in this embodiment into (or through) the piezoelectric layer L2 as well.

[0146] In certain embodiments, the piezoelectric layer L2 is of aluminium nitride, AIN, or of scandium-doped aluminium nitride, Sc-doped AIN. In certain embodiments, the piezoelectric layer has a thickness in a range of 1 pm to 2 pm, preferably in a range of 1.3 pm to 1.7 pm, such as 1.5 pm.

[0147] As shown in Fig. 2d, in certain embodiments, the second region 202 comprises a silicon layer L4 and a trimming material layer 212 on the silicon layer L4. In certain embodiments, the second region 202 comprises silicon, such as doped silicon, such as ultra-heavily doped, UHD, silicon. In certain embodiments, the second region 202 is absent from the piezoelectric layer L2 and the top electrode layer L1.

[0148] In certain embodiments, the trimming material layer 212 is the topmost layer of the material stack of the second region 202. In certain embodiments, the trimming material layer 212 is implemented by a layer of metal, preferably gold (Au). In certain embodiments, the trimming material layer 212 has a thickness in a range of 0.05 pm to 0.6 pm, preferably a range of 0.1 pm to 0.4 pm, such as 0.25 pm.As shown in the embodiment of Fig. 2d, in certain embodiments, the first region 201 and the second region 202 share the same silicon layer L4. In certain embodiments, the top electrode layer L1 and the silicon layer L4 do not touch one another (as it would create a short circuit, within the first region 201 or in between the first region 201 and the second region 202). Within the first region 201, the top electrode layer L1 and the silicon layer L4 are separated by an insulating material layer, which is in this embodiment a piezoelectric layer L2.

[0149] In between the first region 201 and the second region 202, in accordance with certain embodiments, there is a trench or isolation regions 215, or both. In the embodiment shown in Fig. 2d, in the location of the cross-section D-D the first region 201 and the second region 202 are separated from one another by trenches 104. This prevents a short-circuit between the regions 201, 202.

[0150] Figs. 3, 4 and 5 schematically show a top view of a multi-ladder resonator 100 according to an example embodiment. These example resonators 100 comprise multiple resonating elements 101a, 101b, 101c coupled by a coupler 310, the resonators 100 having the first region 201 and the second region 202. What is disclosed above in the context of a single resonating element 101a, 101b, 101c, apply herein as well (depending on the embodiment), in accordance with certain embodiments.

[0151] In the embodiments of Figs. 3, 4 and 5, the resonator 100 comprises a mechanically coupled assembly with multiple ‘ladders’ 101a, 101b to achieve higher resonator area and improved quality factor (Q). In these embodiments, the resonator is a multi-ladder resonator 100, comprising a plurality of stacked resonating elements 101a, 101b (each stacked resonating element 101a, 101b forming a ladder-like configuration). In these embodiments, the resonating elements 101a, 101b comprise a plurality of resonating beam elements positioned adjacent to each other and adjacent beam elements are mechanically connected to each other by connection elements 102, and the resonating beam elements are separated from each other by trenches 104 (forming a ladder-like configuration). In certain embodiments, the resonator 100 is separated from a support structure by an external trench 104’. In certain embodiments, the resonator 100 is coupled to (suspended from) a support structure via anchoring point(s) 103.

[0152] In certain embodiments, the resonator 100 comprises a mechanical coupler 310 which connects the resonating elements to one another. In certain embodiments, the coupler 310 is a flexural coupler 310, such as shown in Fig. 3. In certain embodiments, the coupler 310is a length extensional, LE, coupler 310, such as shown in Figs. 4 and 5. In certain embodiments, the coupler 310 is a rigid coupler 310. In certain embodiments, the coupler 310 is a silicon beam coupler 310. In certain embodiments, the coupler 310 is a Lame mode coupler 310.

[0153] In certain embodiments, the resonator 100 comprises at least a first region 201, and a second region 202. What is disclosed regarding the first region 201 and the second region 202 in the context of Figs. 2a, 2b and 2d, apply herein as well. As shown in Fig. 3, in certain embodiments, the resonator 100 comprises at least one resonating element, in this case a plurality of resonating elements 101a, 101b, each of the resonating elements 101a, 101b comprising the at least one first region 201 and the second region 202. As shown in Fig. 4, in certain embodiments, the resonator 100 comprises at least one resonating element, in this case a plurality of resonating elements 101a, 101b, wherein one (entire) resonating element 101a, 101b forms the first region 201 or the second region 202. In certain embodiments, the coupler 310 forms the first region 201 or the second region 202.

[0154] Accordingly, as shown in both Figs. 3 and 4, in certain embodiments, the resonator 100 comprises at least one first region 201, and a second region 202, wherein the first region 201 comprises at least a top electrode layer L1, and wherein the second region 202 comprises at least a trimming material layer 212.

[0155] In certain embodiments, the first region 201 (or the second regions 202) covers at least one resonating element 101a, 101b. In certain embodiments, the first region 201 and the second region 202 are separated from one another by the couplers 310. In certain embodiments, such as shown in Fig. 3, the couplers 310 (the area of the coupler 310) are comprised into the second region 202. In certain alternative embodiments, the coupler 310 is not part of any region 201, 202.

[0156] As shown in Figs. 3 and 4, the coupler 310 is trimmable as well in certain embodiments. In these embodiments, the coupler 310 comprises trimming material 212. In certain embodiments, in addition to match the trimming rate of the first region 201 and the second region 202, the trimming rate of the coupler 310 is also matched with the first and the second regions 201, 202.

[0157] Fig. 4 schematically shows a top view of an overtone resonator 100 according to another example embodiment. In certain embodiments, the resonator 100 operates in an overtone thereof to achieve higher resonator area and improved quality factor, Q. In certain embodiments, the resonator 100 is configured to operate in an overtone resonancefrequency. In certain embodiments, the resonator 100 is configured to operate in an overtone resonance frequency of N x 32 MHz, wherein N is 2, 3, 4, 5.... In certain embodiments, the resonator 100 is configured to operate in an overtone resonance frequency of 76 MHz. In certain embodiments, the overtone resonance enables providing enhanced equivalent series resistance, ESR, and quality factor, Q.

[0158] As shown in Fig. 4, the first and the second regions 201 , 202 are separated by isolation regions 215. in certain embodiments, the isolation regions extend from trench 104 to trench 104, thereby dividing the resonator 100 into the first region 201 and the second region 202. In certain embodiments, the isolation regions 215 along the width direction (x-direction, x-axis) of the resonating beams. In certain embodiments, the first region 201 and the second region 202 are electrically isolated (different, separated) regions. In certain alternative embodiments, the first region 201 and the second region 202 are separated by inert couplers 310 (not shown).

[0159] As shown in Fig. 4, in certain embodiments, the first region 201 and the second region 202 of the resonator 100 are configured to resonate out-of-phase with one another. This is the case, by way of an example, in Fig. 4, wherein the two first region 201 resonating elements 101a, 101b are configured to resonate in-phase with one another. In this embodiment, the second region 202 (being the coupler 310) is configured to resonate out-of-phase (in comparison to the two first region 201 resonating elements 101a, 101b). In certain alternative embodiments, the first region 201 and the second region 202 of the resonator 100 are configured to resonate in-phase with one another (not shown).

[0160] In certain embodiments, the first region 201 and the second region 202 of the resonator 100 are configured to resonate in the same resonance modes with one another. This is the case, by way of an example, in Fig. 4, wherein the entire resonator 100 is configured to resonate in the length-extensional resonance mode. In certain alternative embodiments, the first region 201 and the second region 202 of the resonator 100 are configured to resonate in different resonance modes with one another.

[0161] Fig. 5 shows an analogous embodiment than Fig. 4, except that the first region 201 and the second region 202 are not arranged in rows like in Fig. 4. In certain embodiments, the first region 201 (resonating beam elements thereof) and the second region 202 (resonating beam elements thereof) are arranged alternatingly or arbitrarily within the resonator 100. Accordingly, the resonator 100 comprises the first region 201 and the second region 202 in a “mix and match” arrangement.In certain embodiments, the first region 201 is provided by a plurality of resonating beam elements. In certain embodiments, the second region 202 is provided by a plurality of resonating beam elements. In certain embodiments, said first 201 and the second region 202 (resonating elements thereof) are arranged in rows (Fig. 4). In certain embodiments, said first 201 and the second region 202 (resonating elements thereof) are arranged alternatingly or arbitrarily (Fig. 5) within the resonator 100.

[0162] In certain embodiments, the coupler 310 is formed of both first region 201 and the second region 202. Accordingly, as shown in both Fig. 5, in certain embodiments, the resonator 100 comprises a plurality of first regions 201 , and a plurality of second regions 202, wherein the first regions 201 comprise at least a top electrode layer L1, and wherein the second regions 202 comprises at least a trimming material layer 212. Herein is further provided an apparatus, such as a resonator array, comprising at least one resonator 100. What is disclosed in context of individual resonator 100 applies also in the context of the apparatus comprising the resonator 100. In certain embodiments, the apparatus is a semiconductor apparatus, or a semiconductor device.

[0163] Fig. 6a shows a schematic top view of a slanted resonator 100 in accordance with certain embodiments. The slanted resonator 100 comprises a slanted resonator (resonating) element, in accordance with certain embodiments. What is disclosed above in the context of first and second region apply herein as well (depending on the embodiment), in accordance with certain embodiments, although not drawn.

[0164] In certain embodiments, the resonator element comprises one or more slanted resonating beams 101. A longitudinal axis 150 of each resonating beam 10T is slanted (tilted) from a <100> direction of silicon in accordance with certain embodiments. In other words, in certain embodiments, each resonating beam 10T is slanted in a skewed manner. Said slanting is to reduce the effect of drive level dependency, DLD.

[0165] In certain embodiments, the longitudinal axis of the resonating beams 10T is slanted 25 to 22 degrees, more preferably 18 to 20 degrees, most preferably 19 degrees from said <100> direction. In accordance with certain embodiments, this is for optimal DLD cancellation in certain embodiments.

[0166] In certain embodiments, as shown in Fig. 2, each resonating beam 101 is in the form of a resonating beam skewed in one (and only one) direction (here: x-direction). Each resonating beam 10T is in the form of a skewed rectangle so that each resonating beam has the formof a parallelogram with adjacent sides of unequal lengths and angles non-right angled (i.e. , rhomboid) in accordance with certain embodiments. In certain embodiments, the resonating beams 10T have an aspect ratio of greater than one. Both ends (shorter edges) of the resonating beams 10T are aligned with a direction perpendicular to said <100> direction, in certain embodiments. This perpendicular direction may be another <100> direction (“second <100> direction”) in the event of single-crystalline silicon, in accordance with certain embodiments. In certain embodiments, the skewed rectangles are skewed along an axis which is both in the plane of the resonator element (preferably a {100} plane) and perpendicular to the first mentioned <100> direction ("first <100> direction”). In certain embodiments, the skewed rectangles are unskewed in said first <100> direction. In certain embodiments, the skewed rectangles are skewed (slanted) 16 to 22 degrees, more preferably 18 to 20 degrees, most preferably 19 degrees from the first <100> direction (about one of the corners of the 15 rectangle).

[0167] In certain embodiments, as shown in Fig. 2, the resonator element comprises anchoring points (suspenders) 103 at nodal points of the resonator element to anchor the resonator element to a surrounding structure. In certain embodiments, a respective suspender 103 is positioned at a center of an outer longer edge of both outermost resonating beams 10T. In certain embodiments, the suspenders 103 are aligned with a direction perpendicular to the longitudinal axis of the resonating beams 10T. In certain embodiments, the suspenders 103 are slanted from the first <100> direction of silicon similarly as the resonating beams 10T.

[0168] Fig. 6b schematically shows a top view of a multi-ladder resonator 100 with slanted couplers according to an example embodiment. The example resonator 100 comprises multiple resonating elements 101a, 101b coupled by slanted coupler(s) 310’. What is disclosed above in the context of a single resonating element apply herein as well (depending on the embodiment), in accordance with certain embodiments. Furthermore, what is disclosed above in the context of first and second region apply herein as well (depending on the embodiment), in accordance with certain embodiments, although not drawn.

[0169] In certain embodiments, the resonating elements 101a and 101b are slanted resonating elements. In certain embodiments, the resonating elements 101a and 101b are coupled to one another by at least one coupler 310’. In certain embodiments, the resonating elements 101a and 101b are coupled to one another by a plurality of coupler 310’.In certain embodiments, the coupler 310’ is a slanted coupler. In certain embodiments, the coupler is a slanted coupler, wherein a longitudinal axis of the slanted coupler is tilted from a <100> direction of silicon.

[0170] In certain embodiments, the slanted resonating elements 101a, 101b are coupled with the slanted resonator couplers 310’. In accordance with certain embodiments, this enhances the transduction, ESR, and FDLD. A longitudinal axis 150 of the coupler 310’ is slanted (tilted) from a <100> direction of silicon in accordance with certain embodiments. In other words, in certain embodiments, the coupler 310’ is slanted in a skewed manner. In certain embodiments, the longitudinal axis of the coupler 310’ is slanted 25 to 22 degrees, more preferably 18 to 20 degrees, most preferably 19 degrees from said <100> direction.

[0171] In certain embodiments, the plurality of couplers 310’ have the same crystal orientation with one another. This ensures a good mode shape, and in addition, that the couplers 310’ to have the same acoustic velocity in resonator 100 and coupler domains. In other words, the slanted couplers 310’ have the same resonance frequencies (and TCFs) with the resonating elements 101a, 101b in accordance with certain preferable embodiments. In certain embodiments, the slanted couplers 310’ share the same length with one another. Without limiting the scope and the interpretation of the patent claims, certain technical effects of one or more of the example embodiments disclosed herein are listed in the following. A technical effect of the invention is providing a resonator having improved quality factor Q. A further technical effect is provision of regions for a transduction purpose, and for high quality factor, Q, purposes within the same resonator device.

[0172] A further technical effect is matching the trimming rates of these regions of the resonator. A further technical effect is enabling trimming of high-Q resonator without performance degradation. A further technical effect is enabling trimming of the device without affecting or decreasing the quality factor Q or causing adverse effects on the resonance frequency stability. In case there is no trimming layer 212 in the second region 202 (the high-quality factor, HQ, region), the trimming process would cause the frequencies of the individual regions (the first region 201 and the second region 202) to get mismatched. This results in the quality factor, Q dropping. The solution according to the instant disclosure fixes that problem.

[0173] A further technical effect is eliminating the need to have complex resonator designs, wherein quality factor Q performance would be only reached after trimming. A further technical effect is enabling preventing thermoelastic dissipation, TED losses of theresonator. A further technical effect is enabling minimal stress / strain modulation caused by the provision trimming material. A further technical effect is enabling good frequency stability.

[0174] A further technical effect is to provide a pin-to-pin compatible resonator (with quartz). A further technical effect is retaining good temperature compensation features of the resonator. A further technical effect is providing a more positive overall temperature coefficient of frequency, TCF. More positive overall TCF is reached due to reduced piezoelectric coverage of the instant solution. Simultaneously, the instant solution enables providing decreased capacitance, and providing enhanced figure of merit, FOM, of the resonator. A further technical effect is providing a resonator having reduced tuning sensitivity due to the reduced capacitance of the resonator.

[0175] Various embodiments have been presented. It should be appreciated that in this document, words comprise, include, and contain are each used as open-ended expressions with no intended exclusivity.

[0176] The foregoing description has provided by way of non-limiting examples of particular implementations and embodiments a full and informative description of the best mode presently contemplated by the inventors for carrying out the invention. It is however clear to a person skilled in the art that the invention is not restricted to details of the embodiments presented in the foregoing, but that it can be implemented in other embodiments using equivalent means or in different combinations of embodiments without deviating from the characteristics of the invention.

[0177] Furthermore, some of the features of the afore-disclosed example embodiments may be used to advantage without the corresponding use of other features. As such, the foregoing description shall be considered as merely illustrative of the principles of the present invention, and not in limitation thereof. Hence, the scope of the invention is only restricted by the appended patent claims.

Claims

CLAIMS1. A resonator,the resonator comprising at least a first region, and a second region, wherein the first region comprises at least a top electrode layer, andwherein the second region comprises at least a trimming material layer.

2. The resonator of claim 1 , wherein the top electrode layer comprises patterns, such as perforations, lines or both.

3. The resonator of claim 1 or 2, wherein the trimming material layer is in a form of patterns, such as localized features, lines or both.

4. The resonator of any of the preceding claims, wherein the first region and the second region each comprise at least one dimension that is different from the corresponding dimension of the other region.

5. The resonator of any of the preceding claims, wherein the material stack of the first region comprises a top electrode layer, a piezoelectric layer, and a silicon layer, wherein the piezoelectric layer is on the silicon layer, and the top electrode layer is on the piezoelectric layer.

6. The resonator of any of the preceding claims, wherein the material stack of the second region comprises a silicon layer and the trimming layer on the silicon layer.

7. The resonator of any preceding claim, wherein the first region and the second region are separated by one another by trench(es) and / or isolation regions.

8. The resonator of any of the preceding claim, comprising a resonating element, or a plurality of resonating elements, wherein the plurality of resonating elements are adjacent to each other in a plane, connected to one another by a coupler.

9. The resonator of claim 8, wherein the resonating element comprises a plurality of resonating beam elements adjacent to each other in a plane, connected to one another by connection elements and separated from one another by trenches.

10. The resonator of claim 8 or 9, wherein the resonating element is a slanted resonator element, wherein a longitudinal axis of the slanted resonating element is tilted from a <100> direction of silicon.

11. The resonator of claim 8, 9, or 10, wherein the coupler is a slanted coupler, wherein a longitudinal axis of the slanted coupler is tilted from a <100> direction of silicon.

12. The resonator of any of the preceding claim, wherein the first region is for providing transduction of the resonator, and the second region is for providing high quality factor, Q, of the resonator.

13. The resonator of any of the preceding claim, wherein the second region of the resonator is configured to resonate in a resonance mode different than the first region, and / or wherein the first region of the resonator is configured to resonate in a lengthextensional, LE, resonance mode.

14. An apparatus, such as a resonator array, comprising at least one resonator according to any of claims 1-13.

15. A method for matching trimming rates of the first region and the second region of the resonator according to any of claims 1-13, the method comprising the steps of:- providing the resonator of according to any of claims 1-13;- removing a part of the top electrode layer of the first region; and- providing the trimming material layer onto the second region.

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